1. Field of the Invention
The present invention relates to a probe card installed in a tester of an apparatus for testing electrical parameters of chips formed on a semiconductor wafer.
2. Description of the Related Art
Before cutting semiconductor wafers containing manufactured logic or memory chips, the electrical parameters of the semiconductor chips are typically tested using a testing apparatus. A conventional testing apparatus typically includes a supporter on which the semiconductor wafer is positioned and a printed circuit board, which is installed between the supporter and a probe station of the tester for use as a probe card. A probe unit, which includes a plurality of probe pins and is used to test the electrical parameters of the chips on the semiconductor wafer, is installed on the printed circuit board such that the plurality of probes are in one-to-one contact with a plurality of terminal pads formed on each of the chips. The probe unit is arranged such that a plurality of chips may be tested simultaneously on a conventional 200 mm (7.9 inches) wafer. In conventional probe cards, probe units are arranged to be capable of satisfactorily testing ten or more chips simultaneously.
However, when the diameter of a semiconductor wafer is increased to over 300 mm (11.8 inches), the conventional probe card may have difficulty in testing such a semiconductor wafer due to the difference in size between the probe card and the semiconductor wafer. In addition, as the diameter of a semiconductor wafer increases, the number of chips that may be formed on the semiconductor wafer may increase two or more times. Accordingly, it becomes more difficult to effectively test such large-sized semiconductor wafers with the use of a testing apparatus having a conventional probe card because of limited processing speed and throughput.
To solve the above-described problems, it is a feature of an embodiment of the present invention to provide a probe card for a testing apparatus head, which is capable of testing the electrical parameters of a larger semiconductor wafer by increasing the size of a printed circuit board.
It is another feature of an embodiment of the present invention to provide a probe card for a testing apparatus head that has improved processing speed by increasing the number of probe units.
A testing apparatus according to the present invention includes 1) a supporting plate on which a semiconductor wafer may be positioned; 2) a tester head having a top plate installed a predetermined distance away from the supporting plate; and 3) a probe card interposed between the supporting plate and the top plate and connected to the top plate. The probe card comprises a multi-layered printed circuit board to which are attached a plurality of test probes, each test probe having a plurality of flexible contacts for temporarily connecting with a plurality of contact pads formed on a chip on the semiconductor wafer. The probe card and the top plate are circular and both preferably have a diameter that is at least 400 mm (15.75 inches). More preferably, the diameter of the printed circuit board is 440 mm (17.32 inches).
The plurality of test probes include a plurality of connecting elements, each element having a plurality of contact pins that are preferably formed on the printed circuit board in order to test the electrical characteristics of the chips formed on the semiconductor wafer. The printed circuit board which preferably is divided into four quadrants with the plurality of connecting elements arranged along the circumference of the printed circuit board such that generally one fourth of the plurality of connecting elements are allotted to each of the four quadrants.
The plurality of connecting elements are preferably elongated or bar-shaped. In order to install additional connecting elements on the printed circuit board, the plurality of connecting elements are preferably arranged radially along the circumference of the printed circuit board. In order to increase the number of pins allotted to a unit length of each of the plurality of connecting elements, 112 contact pins are preferably formed at each one of the plurality of connecting elements such that the contact pins are arranged in two rows with 56 contact pins being allotted to each row. Twenty-four such connecting elements are preferably arranged on each of the four quadrants of the printed circuit board.
The center of each of the plurality of connecting elements is an exemplary 191.5 mm (7.54 inches) away from the central point of the printed circuit board. Two adjacent connecting elements belonging to the same quadrant of the printed circuit board among the plurality of connecting elements form an exemplary angle of 3.5 degrees with each other. A connecting element adjacent to one of four boundaries between adjacent quadrants of the printed circuit board forms an exemplary angle of 4.75 degrees with the boundary. A stiffener fixing hole is preferably formed on any one of four boundaries between adjacent quadrants of the printed circuit board and its opposing boundary. The stiffener fixing hole may be a representative 182.5 mm (7.19 inches) away from the central point of the printed circuit board.
Card holder holes are preferably formed on one of four boundaries between adjacent quadrants of the printed circuit board. Two pairs of card holder holes may be formed at opposing boundaries between adjacent quadrants of the printed circuit board, wherein opposing boundaries are two boundaries separated by 180 degrees. One of the card holder holes may preferably be 197.5 mm (7.78 inches) away from the central point of the printed circuit board and another of the card holder holes may preferably be 214.5 mm (8.44 inches) away from the central point of the printed circuit board.
A guide pin hole is preferably formed on each of four boundaries between adjacent quadrants of the printed circuit board. The guide pin hole may preferably be 207.5 mm (8.17 inches) away from the central point of the printed circuit board.
Preferably, each of the connecting elements comprises a male zero-insertion-force (ZIF) type connector, and a ZIF type female connector is formed at the top plate so as to be coupled with the male ZIF type connector.
The printed circuit board for a tester head is enlarged such that a semiconductor wafer having a diameter at least 300 mm (11.8 inches) may be mounted on the printed circuit board. Thus, it is possible to set standards in measuring the electrical characteristics of a next-generation semiconductor device, and increase the number of chips being processed simultaneously in accordance of the increase of the size of a semiconductor wafer.
These and other features of the present invention will be readily apparent to those of ordinary skill in the art upon review of the detailed description that follows.